Refrigeration device for transportation
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Solution Overview
Problem
Container refrigeration apparatuses face challenges in accurately determining motor abnormalities due to variations in supply voltage and frequency across different countries, leading to erroneous detection of lock and connection abnormalities.
Innovation Solution
Adaptive current thresholds for abnormality determination are adjusted based on supply frequency and voltage, allowing for precise differentiation between normal and abnormal motor operations by setting higher thresholds with increasing voltage and lower thresholds with decreasing voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed current thresholds are used for abnormality determination, then the device complexity is reduced, but the measurement precision deteriorates due to supply voltage and frequency variations
Solution Approach 1:
The patent applies dynamics by making the current thresholds adaptive rather than fixed. The thresholds dynamically adjust based on detected supply voltage and frequency values, allowing the system to maintain high measurement precision across different operating conditions without excessive complexity. The controller automatically recalibrates thresholds based on actual power supply characteristics.
Solution Approach 2:
The patent changes the parameters used for abnormality determination by introducing voltage and frequency as additional variables. Instead of using a single fixed current threshold, the system modifies the threshold parameters based on the detected voltage and frequency values, enabling accurate abnormality detection across different power supply conditions.
2Measurement precision
If adaptive current thresholds based on supply voltage and frequency are implemented, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The system applies self-service by automatically detecting supply voltage and frequency, then autonomously calculating and adjusting the appropriate current thresholds without external intervention. The controller performs all threshold adaptation operations internally based on real-time power supply measurements, eliminating the need for manual calibration or complex external adjustment mechanisms.
Solution Approach 2:
The patent implements feedback by continuously monitoring supply voltage and frequency, then using this information to adjust current thresholds. The system creates a closed-loop control where the detected power supply characteristics feed back into the threshold determination process, ensuring thresholds remain appropriate for current operating conditions.
3Adaptability or versatility
If current thresholds are adjusted for different supply conditions, then the adaptability is improved, but the difficulty of detecting and measuring abnormalities increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing the relationship between supply voltage/frequency and appropriate current thresholds. The system proactively adjusts thresholds based on detected power supply characteristics before abnormalities occur, rather than reacting to abnormalities after they happen. This preliminary calibration simplifies the overall detection process.
Data Source
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AI summary
According to the present disclosure, in a container refrigeration apparatus configured to cool the inside of a container, the accuracy of determination of occurrence of a lock abnormality and a connection abnormality of a motor is increased, and erroneous detection of the motor abnormalities is reduced or prevented. The container refrigeration apparatus of the present disclosure includes an abnormality determinator (44) configured to compare a value for current flowing through an in-compartment motor (1) with a preset current threshold to determine occurrence of the motor abnormalities of the in-compartment motor (1), and a threshold changer (45) configured to change the current threshold of the abnormality determinator (44) in accordance with a supply voltage for each supply frequency of a power supply (42) configured to supply power to the in-compartment motor (1).